The invention relates to a fuel supply system having operative parts that are integrally formed with respect to each other.
Many different versions of fuel supply systems are known. They all comprise a container or main tank, a (fuel) pump and usually also a splash pot (often called a calming vessel or reservoir), from which the pump sucks up. The splash pot is preferably filled, usually by means of a suction jet pump which, in turn, may be fed from the forward run of the pump or from a fuel return.
The pump is often arranged directly in the splash pot, sometimes even combined with the latter to form a fuel feed unit (DE 35 10 890 C2). The latter is introduced, complete, through a recess provided in the tank ceiling and is fastened to the recess edge by means of a closing cover. The splash pot, together with the pump, is led as near as possible to the tank bottom and supported on the latter.
In modern motor vehicles, there is less and less space left for the clear height of the tanks which, instead, have to be wider in order to maintain a sufficient volume. This gives rise to increased splashing movements of the tank content in the plane of the roadway during accelerations. In order, then, to ensure a satisfactory supply of fuel to the pump and engine under all conceivable driving conditions, a large splash pot volume must be provided. However, this can be implemented reasonably only if the splash pot is of relatively great height.
Furthermore, in light of increasingly stringent emission protection regulations, the aim is, if possible, to minimize the number of potential leakage points in the fuel supply system. Attempts are therefore also made to dispense with said recess for introducing the fuel feed unit and, instead, to introduce the latter through the filler orifice which is present in any case. As a result of this, however, there is a conflict between the requirements, on the one hand, of providing as high a splash pot as possible, but, on the other hand, also of having the possibility of exchanging the pump at any time. If the splash pot reaches near to and just below the tank ceiling, the pump can no longer be demounted separately.